The use of beams of radiation to obtain information about an object by detecting the amplitude or phase of the beam is well known for scientific and medical purposes. For example, the phase information of a beam that passes through an object can provide information on the object's temperature, composition, magnetic field or electrostatic field, whereas amplitude measurements can provide information on the opaqueness or density of the object. The beams are comprised of waves of radiation, where a wave can be described as having both an amplitude, A, and phase, φ, described mathematically as,ψ=Aexp(φ)  1)
The information obtained from the diagnostic method depends on whether it is detecting the amplitude or both the amplitude and phase of a beam's wave. If the diagnostic method measures only a beam's amplitude, as is the case for Ultrasound and X-ray, only density differences in the object are reported. If the diagnostic method can detect both the amplitude and phase, it can, for example, provide information on the object's temperature, composition, elasticity, strain field, magnetic or electrostatic fields. For acoustic radiation, i.e., acoustic beams, the phase of a beam is modified by an object's refractive index, where the refractive index is dependent on the object's temperature and composition and is a measure of the acoustic beam's speed of sound. Hence, use of the above prior art limits the information that can be obtained. An additional disadvantage of a number of diagnostic imaging techniques such as X-ray imaging methods is the strength of radiation employed. Levels employed may have the potential to damage cells in the body.
Examples of an application where the measurement of temperature and/or composition is important include medical diagnostics aimed at understanding the function of organs, tissue and diseased regions in the body. Presently medical researchers do not have good means to non-invasively measure the internal temperature and composition of the body.
Confocal scanning laser microscopes were developed in the 1980s for seeing three-dimensional objects. Confocal scanning laser microscopy uses a laser beam passing through an object to create a three-dimensional amplitude image of the object by detecting the amplitude of the beam through a pinhole aperture placed confocal with a point on a focal plane of the object.
Confocal microscopes have now found widespread applications in the materials, biological, and medical sciences. As a diagnostic tool, confocal microscopes are limited to detecting only thin tissue and the density differences of objects, which produce amplitude differences of the detected beam. They do not measure the object's phase information. Hence, confocal microscopes cannot measure an object's composition or temperature.
Standard interferometry microscopes, standard holography microscopes, and standard holographic interferometry microscopes have been used to measure both the phase and the amplitude of objects, giving important information of objects such as their density, composition and temperature. Interferometry microscopes and holographic interferometry microscopes are different from holography microscopes. Interferometry microscopes and holographic interferometry microscopes make relative measurements of the state of an object such as 3 degrees above room temperature whereas holography microscopes make absolute measurements of the state of an object such as a human body having a temperature of 98.6 degrees Fahrenheit. These microscopes create a three dimensional amplitude image and phase image of the object by measuring both the phase and the amplitude. However, the three-dimensional information measured from these microscopes comes only from the surface of the object and not at points within the object.
The concept of marrying the techniques of confocal microscopy and holography using laser beams is disclosed in U.S. Pat. No. 7,639,365, entitled, “Confocal Scanning Holography Microscope”, issued Dec. 29, 2009. The microscopes described in U.S. Pat. No. 7,639,365 measure the absolute phase of the object and cannot be used to image the inside of the human body as laser beams do not readily pass through the human body.
Acoustic microscopes including Ultrasound are now widely used to image the inside of the body such as the fetus in the womb and blood flow in arteries and veins. These microscopes measure the intensity of the acoustic beam reflected off surfaces such as bones and interfaces such as the interface between the embryonic fluid and fetus. These microscopes cannot measure the intensity and phase of the beam passing through or reflected from soft tissue such as muscles or embryonic fluid. These microscopes also cannot measure temperature or composition as they only use the intensity of the acoustic beams and not the phase of the acoustic beams.
Accordingly, it is an object of the present invention to overcome the above deficiencies of the prior art.